Visual Basic 6.0

Call a JavaScript Function Passing an Object Argument

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Demonstrates how to call a JavaScript function with an argument that is an object. Visual Basic 6.0

Dim success As Long
success = 0

' This is the JavaScript function we'll call:

' function describeCar(car) {
' 	console.log(`This is a ${car.year} ${car.make} ${car.model}.`);
' }

Dim sbScript As New ChilkatStringBuilder
success = sbScript.Append("function describeCar(car) { console.log(`This is a ${car.year} ${car.make} ${car.model}.`); }")

Dim js As New ChilkatJs

Dim result As New ChilkatJsonObject
result.EmitCompact = 0

' Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result)
If (success = 0) Then
    ' Examine the result for an exception.
    Debug.Print result.Emit()

    ' Also examine the LastErrorText.
    Debug.Print js.LastErrorText
    Exit Sub
End If

' ------------------------------------------------------------------------------
' Call the function describeCar(car)

Dim funcCall As New ChilkatJsonObject
funcCall.EmitCompact = 0

' Create JSON specifying the function name and arguments
' In this case, there is only 1 argument, and it is an object.

' {
'   "name": "describeCar",
'   "args": [
'     {
'       "make": "Toyota",
'       "model": "Corolla",
'       "year": 2022
'     }
'   ]
' }

success = funcCall.UpdateString("name","describeCar")

' Create the JSON object that is the argument.
Dim arg As New ChilkatJsonObject
success = arg.UpdateString("make","Toyota")
success = arg.UpdateString("model","Corolla")
success = arg.UpdateInt("year",2022)

' Create the arguments array.
Dim argsArray As New ChilkatJsonArray
success = argsArray.AddObjectCopyAt(0,arg)

' Add the "args" array to the funcCall.
success = funcCall.AppendArrayCopy("args",argsArray)

Debug.Print funcCall.Emit()

success = js.CallFunction(funcCall,result)
If (success = 0) Then
    ' Examine the result for an exception.
    Debug.Print result.Emit()

    ' Also examine the LastErrorText.
    Debug.Print js.LastErrorText
    Exit Sub
End If

Debug.Print result.Emit()

' The describeCar JavaScript function returns nothing. 
' Therefore, the result is "undefined".

' {
'   "type": "undefined",
'   "value": "undefined"
' }

' However, the function emitted text to the console.

Dim sbOut As New ChilkatStringBuilder
js.ConsoleOutputSb sbOut
Debug.Print sbOut.GetAsString()

' Output:
' This is a 2022 Toyota Corolla.

' -----------------------------------------------------------
' Note: If the object argument is simple, this is an alternative
' and simpler way of creating the funcCall:

funcCall.Clear 
success = funcCall.UpdateString("name","describeCar")
success = funcCall.UpdateString("args[0].make","Toyota")
success = funcCall.UpdateString("args[0].model","Corolla")
success = funcCall.UpdateInt("args[0].year",2022)
Debug.Print funcCall.Emit()